I'm trying to run multiple mutations in the same transaction. To my understanding something like this should work: ``` runMutations = async (mutations: DGraphJS.Mutation[]): Promise<DGraphJS.Response> => { const txn = this.client.newTxn(); try { const req = new DGraphJS.Request(); req.setCommitNow(true); req.setMutationsList(mutations); return txn.doRequest(req); } finally { await txn.discard(); } } ``` However this throws the following error: ``` StartTs cannot be zero while committing a transaction ``` What's weird to me is all of the mutations work when using this function. Is this error a bug, or am I doing something wrong?